Freescale Semiconductor Data Sheet MWCT1012DS Features • • • • • • • • • • • • Compliant with the latest version Wireless Power Consortium (WPC) specifications transmitter design Supports wide DC input voltage ranging from 4.2 V, typically 12 V and 19 V Integrated digital demodulation Supports two-way communication, transmitter to receiver by FSK and receiver to transmitter by ASK Supports all types of receiver modulation strategies (AC capacitor, AC resistor, and DC resistor) Supports Medium Power Foreign Object Detection (FOD) Framework Supports low standby power Supports various power control techniques: frequency control, duty cycle control, phase shift control and topology switch LED for system status indication Over-voltage/current/temperature protection Software-based solution to provide maximum design freedom and product differentiation FreeMASTER GUI tool to enable configuration, calibration, and debugging Applications • Medium Power Wireless Power Transmitter Medium power consumer power transmitter solution with frequency and duty cycle control, phase-shift control, and topology switch (WPC MP-Ax types or customer properties) Document Number: WCT1012DS Rev. 1.1, 09/2015 The WCT1012 is a wireless power transmitter controller that integrates all required functions for the WPC “Qi” compliant wireless power transmitter design. It is an intelligent device that works with the Freescale touch sensing technology or uses periodically analog PING to detect a mobile device for charging while gaining super low standby power. Once the mobile device is detected, the WCT1012 controls the power transfer by adjusting operation frequency and duty cycle, or switching topology, or adjusting the phase shift according to message packets sent by mobile device. In order to maximize the design freedom and product differentiation, the WCT1012 supports medium power consumer power transmitter design (WPC MP-Ax or customization) by using operation frequency and duty cycle control, phase shift control, and topology switch by software based solutions, which can support wireless charging with both medium power receiver and low power receiver. In addition, the easy-to-use FreeMASTER GUI tool has configuration, calibration, and debugging functions to provide a user-friendly design experience and reduced time-to-market. The WCT1012 includes a digital demodulation module to reduce external components, FSK modulation to support two-way communication, and over-voltage/current/temperature protection and FOD module to protect from overheating by misplaced metallic foreign objects. It also handles any abnormal condition and operational status, and provides comprehensive indicator outputs for robust system design. Overview Description Wireless Charging System Functional Diagram © 2015 Freescale Semiconductor, Inc. All rights reserved. _______________________________________________________________________ Contents 1 Absolute Maximum Ratings .................................................................................................................... 5 1.1 Electrical operating ratings...................................................................................................................................... 5 1.2 Thermal handling ratings ........................................................................................................................................ 6 1.3 ESD handling ratings ............................................................................................................................................... 6 1.4 Moisture handling ratings ....................................................................................................................................... 6 2 Electrical Characteristics ......................................................................................................................... 7 2.1 General characteristics ............................................................................................................................................ 7 2.2 Device characteristics.............................................................................................................................................. 9 2.3 Thermal operating characteristics ......................................................................................................................... 14 3 Typical Performance Characteristics ............................................................................................... 15 3.1 System efficiency .................................................................................................................................................. 15 3.2 Standby power ...................................................................................................................................................... 15 3.3 Digital demodulation ............................................................................................................................................ 15 3.4 Two-way communication ...................................................................................................................................... 16 3.5 Foreign object detection ....................................................................................................................................... 16 4 Device Information ................................................................................................................................. 17 4.1 Functional block diagram ...................................................................................................................................... 17 4.2 Pinout diagram ..................................................................................................................................................... 18 4.3 Pin function description ........................................................................................................................................ 18 4.4 Ordering information ............................................................................................................................................ 20 4.5 Package outline drawing ....................................................................................................................................... 20 WCT1012DS, Rev. 1.1, 09/2015 2 Freescale Semiconductor 5 Wireless Charging System Operation Principle ............................................................................ 21 5.1 Fundamentals ....................................................................................................................................................... 21 5.2 Power transfer ...................................................................................................................................................... 21 5.3 Receiver to transmitter communication................................................................................................................ 22 5.4 Transmitter to receiver communication ................................................................................................................ 25 5.5 System control state machine ............................................................................................................................... 27 5.6 Standby power ...................................................................................................................................................... 30 5.7 Foreign object detection ....................................................................................................................................... 30 6 Application Information........................................................................................................................ 31 6.1 On-board regulator ............................................................................................................................................... 31 6.2 Inverter and driver control .................................................................................................................................... 31 6.3 Primary coil and resonant capacitor ...................................................................................................................... 32 6.4 Low power control ................................................................................................................................................ 34 6.5 GPIO touch sensor................................................................................................................................................. 34 6.6 ADC input channels ............................................................................................................................................... 34 6.7 Faults handling/recovery ...................................................................................................................................... 35 6.8 LEDs function ........................................................................................................................................................ 36 6.9 Configurable pins .................................................................................................................................................. 37 6.10 Unused pins .......................................................................................................................................................... 38 6.11 Power-on reset ..................................................................................................................................................... 38 6.12 External reset ........................................................................................................................................................ 38 6.13 Programming & Debug interface ........................................................................................................................... 38 6.14 Software module .................................................................................................................................................. 38 6.15 Example design schematics ................................................................................................................................... 40 WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 3 7 Design Considerations ........................................................................................................................... 41 7.1 Electrical design considerations ............................................................................................................................ 41 7.2 PCB layout considerations ..................................................................................................................................... 41 7.3 Thermal design considerations.............................................................................................................................. 42 8 Links ............................................................................................................................................................. 44 WCT1012DS, Rev. 1.1, 09/2015 4 Freescale Semiconductor 1 Absolute Maximum Ratings 1.1 Electrical operating ratings Table 1 Absolute maximum electrical ratings (VSS = 0 V, VSSA = 0 V) Characteristic Symbol Notes 1 Min. Max. Unit Supply Voltage Range VDD –0.3 4.0 V Analog Supply Voltage Range VDDA –0.3 4.0 V ADC High Voltage Reference VREFHx –0.3 4.0 V Voltage difference VDD to VDDA ΔVDD –0.3 0.3 V Voltage difference VSS to VSSA ΔVss –0.3 0.3 V Digital Input Voltage Range VIN Pin Group 1 –0.3 5.5 V RESET Input Voltage Range VIN_RESET Pin Group 2 –0.3 4.0 V Analog Input Voltage Range VINA Pin Group 3 –0.3 4.0 V VIC – –5.0 mA VOC – ±20.0 mA IICont –25 25 mA Input clamp current, per pin (VIN < VSS - 0.3 V) Output clamp current, per pin 2, 3 4 Contiguous pin DC injection current—regional limit sum of 16 contiguous pins Output Voltage Range (normal push-pull mode) VOUT Pin Group 1,2 –0.3 4.0 V Output Voltage Range (open drain mode) VOUTOD Pin Group 1 –0.3 5.5 V VOUTOD_RESET Pin Group 2 –0.3 4.0 V Output Voltage Range Ambient Temperature TA –40 85 °C Storage Temperature Range (Extended Industrial) TSTG –55 150 °C 1. 2. 3. 4. Default Mode: o Pin Group 1: GPIO, TDI, TDO, TMS, TCK o Pin Group 2: o Pin Group 3: ADC and Comparator Analog Inputs Continuous clamp current. All 5 volt tolerant digital I/O pins are internally clamped to VSS through an ESD protection diode. There is no diode connection to VDD. If VIN greater than VDIO_MIN (= VSS–0.3 V) is observed, then there is no need to provide current limiting resistors at the pads. If this limit cannot be observed, then a current limiting resistor is required. I/O is configured as push-pull mode. WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 5 1.2 Thermal handling ratings Table 2 Thermal handling ratings Symbol Description Min. Max. Unit Notes TSTG Storage temperature –55 150 °C 1 TSDR Solder temperature, lead-free – 260 °C 2 1. 2. Determined according to JEDEC Standard JESD22-A103, High Temperature Storage Life. Determined according to IPC/JEDEC Standard J-STD-020, Moisture/Reflow Sensitivity Classification for Nonhermetic Solid State Surface Mount Devices. 1.3 ESD handling ratings Table 3 ESD handling ratings Characteristic 1 Min. Max. Unit ESD for Human Body Model (HBM) -2000 +2000 V ESD for Machine Model (MM) -200 +200 V ESD for Charge Device Model (CDM) -500 +500 V Latch-up current at TA= 85°C (ILAT) -100 +100 mA 1. Parameter is achieved by design characterization on a small sample size from typical devices under typical conditions unless otherwise noted. 1.4 Moisture handling ratings Table 4 Moisture handling ratings Symbol MSL 1. Description Moisture sensitivity level Min. – Max. 3 Unit – Notes 1 Determined according to IPC/JEDEC Standard J-STD-020, Moisture/Reflow Sensitivity Classification for Nonhermetic Solid State Surface Mount Devices. WCT1012DS, Rev. 1.1, 09/2015 6 Freescale Semiconductor 2 Electrical Characteristics 2.1 General characteristics Table 5 General electrical characteristics Recommended operating conditions (VREFLx = 0 V, VSSA = 0 V,VSS = 0 V) Characteristic 2 Symbol Notes Min. Supply Voltage VDD ,VDDA 2.7 ADC Reference Voltage High VREFHA VDDA -0.6 Typ. 3.3 Max. Test Unit conditions 3.6 V - VDDA V - VREFHB Voltage difference VDD to VDDA ΔVDD -0.1 0 0.1 V - Voltage difference VSS to VSSA ΔVss -0.1 0 0.1 V - Input Voltage High (digital inputs) VIH 1 (Pin Group 1) 0.7×VDD 5.5 V - VIH_RESET 1 (Pin Group 2) 0.7×VDD VDD V - VIL 1 (Pin Group 0.35×VDD V - mA Voltage High Input Voltage Low (digital inputs) - 1,2) Output Source Current High (at VOH min.) • IOH 3,4 Programmed for low drive 1 (Pin Group 1) - -2 1 (Pin Group 1) - -9 strength • Programmed for high drive strength Output Source Current High (at VOL max.) • • - IOL 3,4 1 (Pin Group - 2 Programmed for low drive 1,2) - 9 strength 1 (Pin Group Programmed for high drive 1,2) mA strength Output Voltage High VOH 1 (Pin Group 1) VDD -0.5 - - V IOH = IOHmax Output Voltage Low VOL 1 (Pin Group - - 0.5 V IOL = IOLmax - 0 +/-2.5 µA VIN = 2.4 V to 5.5 V 1,2) Digital Input Current High IIH 1 (Pin Group 1) pull-up enabled or disabled 1 (Pin Group 2) VIN = 2.4 V to VDD WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 7 Comparator Input Current High IIHC Internal Pull-Up Resistance RPull-Up Internal Pull-Down Resistance RPull-Down Comparator Input Current Low IILC 1 IOZ Output Current High Impedance 0 +/-2 µA VIN = VDDA 20 - 50 kΩ - 20 - 50 kΩ - 1 (Pin Group 3) - 0 +/-2 µA VIN = 0V 1 (Pin Group - 0 +/-1 µA - 0.06×VDD - - V - 1 (Pin Group 3) State 1,2) Schmitt Trigger Input Hysteresis VHYS 1 (Pin Group 1,2) Input capacitance CIN - 10 - pF - Output capacitance COUT - 10 - pF - 1.5 - - Bus - GPIO pin interrupt pulse width 5 TINT_Pulse 6 clock Port rise and fall time (high drive TPort_H_DIS 7 5.5 - 15.1 ns strength). Slew disabled. 2.7 ≤ VDD ≤ 3.6V Port rise and fall time (high drive strength). Slew enabled. TPort_H_EN 7 1.5 - 6.8 ns 2.7 ≤ VDD ≤ 3.6V Port rise and fall time (low drive strength). Slew disabled. TPort_L_DIS 8 8.2 - 17.8 ns 2.7 ≤ VDD ≤ 3.6V Port rise and fall time (low drive strength). Slew enabled. TPort_L_EN 8 3.2 - 9.2 ns 2.7 ≤ VDD ≤ 3.6V Device (system and core) clock frequency fSYSCLK 0.001 - 100 MHz - Bus clock fBUS - - 50 MHz - 1. 2. 3. 4. 5. 6. 7. 8. Default Mode o Pin Group 1: GPIO, TDI, TDO, TMS, TCK o Pin Group 2: o Pin Group 3: ADC and Comparator Analog Inputs ADC specifications are not guaranteed when VDDA is below 3.0 V. Total chip source or sink current cannot exceed 75mA. Contiguous pin DC injection current of regional limit—including sum of negative injection currents or sum of positive injection currents of 16 contiguous pins—is 25mA. Applies to a pin only when it is configured as GPIO and configured to cause an interrupt by appropriately programming GPIOn_IPOLR and GPIOn_IENR. The greater synchronous and asynchronous timing must be met. 75 pF load 15 pF load WCT1012DS, Rev. 1.1, 09/2015 8 Freescale Semiconductor 2.2 Device characteristics Table 6 General device characteristics Power mode transition behavior Symbol TPOR Description After a POR event, the amount of delay from when Min. Max. Unit 199 225 µs Notes VDD reaches 2.7 V to when the first instruction executes (over the operating temperature range). TS2R STOP mode to RUN mode 6.79 7.27 µs 1 TLPS2LPR LPS mode to LPRUN mode 240.9 551 µs 2 Reset and interrupt timing Symbol tRA tRDA Characteristic Minimum Assertion Duration desertion to First Address Fetch Min. Max. Unit Notes 16 - ns 3 865 × TOSC + - ns 4 570.9 ns 8 × TSYSCLK tIF Delay from Interrupt Assertion to Fetch of first 361.3 instruction (exiting STOP mode) PMC Low-Voltage Detection (LVD) and Power-On Reset (POR) parameters Symbol Characteristic 5 VPOR_A POR Assert Voltage VPOR_R POR Release Voltage VLVI_2p7 VLVI_2p2 Min. Typ. Max. Unit - 2.0 - V - 2.7 - V LVI_2p7 Threshold Voltage - 2.73 - V LVI_2p2 Threshold Voltage - 2.23 - V 6 JTAG timing Symbol Description Min. Max. Unit fOP TCK frequency of operation DC fSYSCLK/8 MHz tPW TCK clock pulse width 50 - ns tDS TMS, TDI data set-up time 5 - ns tDH TMS, TDI data hold time 5 - ns tDV TCK low to TDO data valid - 30 ns tTS TCK low to TDO tri-state - 30 ns Notes Regulator 1.2 V parameters Symbol Characteristic Min. Typ. Max. Unit WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 9 VCAP Output Voltage 7 8 - 1.22 - V ISS Short Circuit Current - 600 - mA TRSC Short Circuit Tolerance (VCAP shorted to ground) - - 30 Mins VREF Reference Voltage (after trim) - 1.21 - V Phase-locked loop timing Symbol fRef_PLL fOP_PLL Characteristic 9 PLL input reference frequency 10 PLL output frequency 11 tLock_PLL PLL lock time tDC_PLL Allowed Duty Cycle of input reference Min. Typ. Max. Unit 8 8 16 MHz 200 - 400 MHz 35.5 - 73.2 µs 40 50 60 % Relaxation oscillator electrical specifications Symbol fROSC_8M fROSC_8M_Delta fROSC_200k fROSC_200k_Delt a tStab tDC_ROSC Characteristic Min. Typ. Max. Unit 12 8 MHz Output Frequency RUN Mode • 0°C to 105°C • -40°C to 105°C Standby Mode (IRC trimmed @ 8 MHz) • -40°C to 105°C 7.84 8 8.16 MHz 7.76 8 8.24 MHz - 405 - kHz - +/-1.5 +/-1.5 +/-2 +/-3 % % 194 200 206 kHz - +/-1.5 +/-1.5 +/-2 +/-3 % % Stabilization Time 14 • 8 MHz output 15 • 200 kHz output - 0.12 10 - µs µs Output Duty Cycle 48 50 52 % 8 MHz Frequency Variation over 25°C RUN Mode Due to temperature • 0°C to 105°C • -40°C to 105°C 13 200 kHz Output Frequency RUN Mode • -40°C to 105°C 200 kHz Output Frequency Variation over 25°C RUN Mode Due to temperature • 0°C to 85°C • -40°C to 105°C Flash specifications Symbol thvpgm4 thversscr thversall Description Longword Program high-voltage time Sector Erase high-voltage time Erase All high-voltage time 16 16 Min. Typ. Max. Unit - 7.5 18 µs - 13 113 ms - 52 452 ms WCT1012DS, Rev. 1.1, 09/2015 10 Freescale Semiconductor trd1sec1k Read 1s Section execution time (flash sector) tpgmchk Program Check execution time 17 trdrsrc Read Resource execution time 17 tpgm4 Program Longword execution time tersscr Erase Flash Sector execution time trd1all Read 1s All Blocks execution time Read Once execution time tpgmonce Program Once execution time tvfykey tflashretp10k tflashretp1k nflashcyc 18 17 trdonce tersall 17 Erase All Blocks execution time 18 Verify Backdoor Access Key execution time 17 Data retention after up to 10 K cycles - 60 µs - - 45 µs - - 30 µs - 65 145 µs - 14 114 ms - - 0.9 ms - - 25 µs - 65 - µs - 70 575 ms - - 30 µs - years - years - cycles 5 Data retention after up to 1 K cycles Cycling endurance - 50 20 20 19 100 19 19 10 K 50 K 12-bit ADC electrical specifications Symbol VDDA fADCCLK Characteristic Supply voltage Min. 21 22 ADC conversion clock 23 Typ. Max. Unit 3 3.3 3.6 V 0.1 - 10 MHz VREFL - VREFH V 0 - VDDA V - 8 - tADCCLK RADC Conversion range with single-ended/unipolar VADCIN Input voltage range (per input) with internal reference tADC Conversion time tADCPU ADC power-up time (from adc_pdn) - 13 - tADCCLK IADCRUN ADC RUN current (per ADC block) - 1.8 - mA - +/- 1.5 +/- 2.2 LSB 25 26 24 27 INLADC Integral non-linearity DNLADC Differential non-linearity - +/- 0.5 +/- 0.8 LSB EGAIN Gain Error - 0.996 to 1.004 0.99 to 1.101 - ENOB Effective number of bits - 10.6 - bits 28 - - +/-3 mA - 4.8 - pF 26 IINJ Input injection current CADCI Input sampling capacitance 27 Comparator and 6-bit DAC electrical specifications Symbol Description Min. Typ. Max. Unit VDD Supply voltage 2.7 - 3.6 V IDDHS Supply current, High-speed mode(EN=1, PMODE=1) - 300 - µA IDDLS Supply current, Low-speed mode(EN=1, PMODE=0) - 36 - µA VAIN Analog input voltage Vss - VDD V WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 11 VAIO Analog input offset voltage VH Analog comparator hysteresis • CR0[HYSTCTR]=00 • CR0[HYSTCTR]=01 • CR0[HYSTCTR]=10 • CR0[HYSTCTR]=11 29 - - 20 mV - 5 13 mV - 25 48 mV - 55 105 mV - 80 148 mV VCMPOh Output high VDD -0.5 - - V VCMPOl Output low - - 0.5 V tDHS Propagation delay, high-speed mode (EN=1, - 25 50 ns - 60 200 ns PMODE=1) tDLS 30 Propagation delay, low-speed mode (EN=1, PMODE=0) 30 31 tDInit Analog comparator initialization delay - 40 - µs IDAC6b 6-bit DAC current adder (enabled) - 7 - µA RDAC6b 6-bit DAC reference inputs VDDA - VDD V INLDAC6b 6-bit DAC integral non-linearity -0.5 - 0.5 LSB DNLDAC6b 6-bit DAC differential non-linearity -0.3 - 0.3 LSB 32 PWM timing parameters Symbol Characteristic 33,34 Min. Typ. Max. Unit fPWM PWM clock frequency - 100 - MHz SPWMNEP NanoEdge Placement (NEP) step size - 312 - ps tDFLT Delay for fault input activating to PWM output deactivated 1 - - ns tPWMPU Power-up time - 25 - μs 35 Timer timing Symbol Characteristic Min. Max. Unit Notes PIN Timer input period 2Ttimer + 6 - ns 36 PINHL Timer input high/low period 1Ttimer + 3 - ns 36 POUT Timer output period 2Ttimer - 2 - ns 36 POUTHL Timer output high/low period 1Ttimer - 2 - ns 36 SCI timing Symbol Characteristic Min. Max. Unit BRSCI Baud rate - (fMAX_SCI /16) Mbit/s PW RXD RXD pulse width 0.965/BRSCI 1.04/BRSCI ns PW TXD TXD pulse width 0.965/BRSCI 1.04/BRSCI ns Notes 37 WCT1012DS, Rev. 1.1, 09/2015 12 Freescale Semiconductor IIC timing Min. Symbol Max. Characteristic Unit Min. Max. Min. fSCL SCL clock frequency 0 100 0 400 kHz tHD_STA Hold time (repeated) START condition. After this period, the first clock pulse is generated. 4 - 0.6 - µs tSCL_LOW LOW period of the SCL clock 4.7 - 1.3 - µs tSCL_HIGH HIGH period of the SCL clock 4 - 0.6 - µs tSU_STA Set-up time for a repeated START condition 4.7 0.6 - tHD_DAT Data hold time for IIC bus devices 0 - 38 tSU_DAT Data set-up time 250 tr Rise time of SDA and SCL signals tf 3.45 41 39 0 40 - 100 - 1000 Fall time of SDA and SCL signals - tSU_STOP Set-up time for STOP condition tBUS_Free tSP 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 0.9 42 Notes Max. µs 38 µs - ns 20 + 0.1Cb 300 ns 43 300 20 + 0.1Cb 300 ns 42, 43 4 - 0.6 - µs Bus free time between STOP and START condition 4.7 - 1.3 - µs Pulse width of spikes that must be suppressed by the input filter N/A N/A 0 50 ns Clock configuration: CPU and system clocks= 100 MHz; Bus Clock = 100 MHz. CPU clock = 200 kHz and 8 MHz IRC on standby. pin filter is enabled by setting the RST_FLT bit in the SIM_CTRL register to 1, the minimum pulse assertion must be If the greater than 21 ns. TOSC means oscillator clock cycle; TSYSCLK means system clock cycle. During 3.3 V VDD power supply ramp down During 3.3 V VDD power supply ramp up (gated by LVI_2p7) Value is after trim Guaranteed by design An externally supplied reference clock should be as free as possible from any phase jitter for the PLL to work correctly. The PLL is optimized for 8 MHz input. The frequency of the core system clock cannot exceed 50 MHz. If the NanoEdge PWM is available, the PLL output must be set to 400 MHz. This is the time required after the PLL is enabled to ensure reliable operation. Frequency after application of 8 MHz trimmed. Frequency after application of 200 kHz trimmed. Standby to run mode transition. Power down to run mode transition. Maximum time based on expectations at cycling end-of-life. Assumes 25 MHz flash clock frequency. Maximum times for erase parameters based on expectations at cycling end-of-life. Typical data retention values are based on measured response accelerated at high temperature and derated to a constant 25°C use profile. Engineering Bulletin EB618 does not apply to this technology. Typical endurance defined in Engineering Bulletin EB619. Cycling endurance represents number of program/erase cycles at -40°C ≤ Tj ≤ 125°C. The ADC functions up to VDDA = 2.7 V. When VDDA is below 3.0 V, ADC specifications are not guaranteed. ADC clock duty cycle is 45% ~ 55%. Conversion range is defined for x1 gain setting. For x2 and x4 the range is 1/2 and 1/4, respectively. In unipolar mode, positive input must be ensured to be always greater than negative input. First conversion takes 10 clock cycles. WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 13 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. INLADC/DNLADC is measured from VADCIN = VREFL to VADCIN = VREFH using Histogram method at x1 gain setting. Least Significant Bit = 0.806 mV at 3.3 V VDDA, x1 gain setting. The current that can be injected into or sourced from an unselected ADC input without affecting the performance of the ADC. Typical hysteresis is measured with input voltage range limited to 0.6 to VDD-0.6V. Signal swing is 100 mV. Comparator initialization delay is defined as the time between software writes to change control inputs (Writes to DACEN, VRSEL, PSEL, MSEL, VOSEL) and the comparator output settling to a stable level. 1 LSB = Vreference/64. Reference IPbus clock of 100 MHz in NanoEdge Placement mode. Temperature and voltage variations do not affect NanoEdge Placement step size. Powerdown to NanoEdge mode transition. Ttimer = Timer input clock cycle. For 100 MHz operation, Ttimer = 10 ns. fMAX_SCI is the frequency of operation of the SCI clock in MHz, which can be selected as the bus clock (max. 50 MHz depending on part number) or 2x bus clock (max. 100 MHz) for the device. The master mode I2C deasserts ACK of an address byte simultaneously with the falling edge of SCL. If no slaves acknowledge this address byte, then a negative hold time can result, depending on the edge rates of the SDA and SCL lines. The maximum tHD_DAT must be met only if the device does not stretch the LOW period (tSCL_LOW) of the SCL signal. Input signal Slew = 10 ns and Output Load = 50 pF Set-up time in slave-transmitter mode is 1 IPBus clock period, if the TX FIFO is empty. 42. A Fast mode IIC bus device can be used in a Standard mode IIC bus system, but the requirement tSU_DAT ≥ 250 ns must then be met. This occurs when the device does not stretch the LOW period of the SCL signal. If such a device does stretch the LOW period of the SCL signal, then it must output the next data bit to the SDA line trmax + tSU_DAT = 1000 + 250 = 1250ns (according to the Standard mode I2C bus specification) before the SCL line is released. 43. Cb = total capacitance of the one bus line in pF. 2.3 Thermal operating characteristics Table 7 General thermal characteristics Symbol Description Min Max Unit TJ Die junction temperature -40 125 °C TA Ambient temperature -40 85 °C WCT1012DS, Rev. 1.1, 09/2015 14 Freescale Semiconductor 3 Typical Performance Characteristics 3.1 System efficiency The maximum system efficiency (RX output power vs. TX input power) on WCT-15W1COILTX solution with MP Qi Receiver (RX) Simulator is more than 75%. Figure 1 System efficiency on the WCT-15W1COILTX solution Note: Power components are the main factor to determine the system efficiency, such as drivers and MOSFETs. The efficiency data in Figure 1 is obtained on the Freescale reference solution with MP TX WCT-15W1COILTX configuration. 3.2 Standby power The WCT1012 solution only consumes very low standby power with special low power control method, and can further achieve ultra low standby power by using the touch sensor technology. Transmitter (TX) power consumption in standby mode with analog PING: < 8mA (96mW with 12 V DC input) 3.3 Digital demodulation The WCT1012 solution employs digital demodulation algorithm to communicate with RX. This method can achieve high performance, low cost, very simple coil signal sensing circuit with less component number. WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 15 3.4 Two-way communication The WCT1012 solution supports two-way communication and uses FSK to send messages to RX. This method allows TX to negotiate with RX to establish advanced power transfer contract, and calibrate power loss for more precise FOD protection. 3.5 Foreign object detection The WCT1012 solution supports medium power FOD framework, which is based on calibrated power loss method and quality factor (Q factor) method. WCT1012DS, Rev. 1.1, 09/2015 16 Freescale Semiconductor 4 Device Information 4.1 Functional block diagram From Figure 2, the low power feature with Freescale touch technology is optional according to user requirements for minimizing standby power. When this function is not deployed, its pin can be configured for other purpose of use. Besides, 10 pins (dashed) are also configurable for different design requirements to provide design freedom and differentiation. Figure 2 WCT1012 functional block diagram WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 17 4.2 Pinout diagram Figure 3 WCT1012 pin configuration (32-pin QFN) 4.3 Pin function description By default, each pin is configured for its primary function (listed first). Any alternative functionality, shown in parentheses, must be programmed through FreeMASTER GUI tool. Table 8 Pin signal descriptions Signal name Pin Type Function description No. TCK TEMP_S TOUCH_S LED1 1 Input Test clock input, connected internally to a pull-up resistor 2 Input A direct hardware reset, when RESET is asserted low, device is initialized and placed in the reset state. Connect a pull-up resistor and decoupling capacitor 3 Output Analog switch selection to extend analog input number Input/Output General purpose input/output pin Input GPIO touch sensor input Input/Output General purpose input/output pin Output LED drive output for system status indicator Input/Output General purpose input/output pin 4 5 WCT1012DS, Rev. 1.1, 09/2015 18 Freescale Semiconductor IN_VOL 6 Input Input voltage detection, analog input pin TEMP 7 Input Temperature detection, analog input pin IN_CURR 8 Input Input current detection, analog input pin VDDA 9 Supply Analog power to on-chip analog module VSSA 10 Supply Analog ground to on-chip analog module Q_TEST 11 Input Q factor detection, analog input pin DACB_0 12 Output DAC output for Q factor detection COIL_CURR 13 Input Primary coil current detection, analog input pin VSS1 14 Supply Digital ground to on-chip digital module GAIN_SWITCH 15 Output Switch the gain of primary coil current detecting circuit Input/Output General purpose input/output pin Input QSCI receive data pin Input/Output General purpose input/output pin Output QSCI transmit data pin Input/Output General purpose input/output pin RXD0 TXD0 16 17 PORT1 18 Input/Output General purpose input/output pin LED2 19 Output LED drive output for system status indicator Input/Output General purpose input/output pin Q_EN 20 Output Q factor detection control pin, enable: low level; disable: high level PWM2 21 Output PWM output 2, control one half of inverter bridge PWM1 22 Output PWM output 1, control another half of inverter bridge PORT2 23 Input/Output General purpose input/output pin Q_S 24 Output Output pin for Q factor detection AUXP_CTRL 25 Output Auxiliary power control pin, enable: high level; disable: low level Input/Output General purpose input/output pin Output Pre-driver chip output enable pin, enable: high level; disable: low level Input/Output General purpose input/output pin DRIVER_EN 26 VCAP 27 Supply Connect a 2.2μF or greater bypass capacitor between this pin and VSS VDD 28 Supply Digital power to on-chip digital module WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 19 VSS2 29 Supply Digital ground to on-chip digital module TDO 30 Output Test data output TMS 31 Input Test mode select input, connect a pull-up resistor to VDD TDI 32 Input Test data input, connected internally to a pull-up resistor 4.4 Ordering information Table 9 lists the pertinent information needed to place an order. Consult a Freescale Semiconductor sales office or authorized distributor to determine availability and to order this device. Table 9 WCT1012 ordering information Device MWCT1012 4.5 Supply voltage 2.7 to 3.6V Package type Quad Flat No-leaded (QFN) Pin count 32 Ambient temp. -40 to +85℃ Order number MWCT1012CFM Package outline drawing To find a package drawing, go to freescale.com and perform a keyword search for the drawing’s document number of 98ASA00473D. WCT1012DS, Rev. 1.1, 09/2015 20 Freescale Semiconductor 5 Wireless Charging System Operation Principle 5.1 Fundamentals Figure 4 Working principle of the Wireless Charging System The Wireless Charging system works as the digital switch mode power supply with the transformer, which is separated into two parts: The primary coil of transformer is placed on the transmitter, working as the TX coil, and the secondary coil of transformer is placed on the receiver side as the RX coil. The basic system working principle diagram is shown in Figure 4. As this system works based on magnetic induction, and better coupling between the TX coil and RX coil gains better system efficiency, so the RX coil should be closely and center aligned with the TX coil as possible. After the RX coil receives the power from the TX coil by magnetic field, it regulates the received voltage to power the load, and send its operational information to TX according to specific protocol by the communication link. Before entering power transfer, TX also sends its operational information to RX for advanced power transfer contract establishing. Then the system can achieve the closed-loop control, and power the load stably and wirelessly. 5.2 Power transfer When the wireless charging receiver is centrally placed on the transmitter coil, and, at the same time, the required conditions are met, the power transfer starts. • The TX coil and RX coil meet proper specifications, such as the inductance, coil dimensions, coil materials, and magnets shielding. • The distance is in suitable range (less than 6 mm for Z axis) between the TX coil and RX coil. • The RX coil should be in the active area of the TX charging surface, which means that the TX coil and RX coil should be well coupled. Coil’s coupling factor highly impacts the power transfer efficiency, and good coupling can achieve high efficiency. The coil shielding is also important, because the magnetic field leaking into the air does not transfer power from TX to RX, and the shielding can contain the magnetic field as much as possible to improve the WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 21 system efficiency and avoid bad effect of the nearby objects from interference. The shielding should be designed to place at the back of the TX coil and RX coil. The power transfer must function correctly under the conditions when the RX coil is placed on the TX charging area during the overall system operational phases. To facilitate power transfer control, set the system operating frequency on the right side of resonant frequency of resonant network (because resonant converter works in a soft-switching mode when its operational frequency is over the resonant frequency and its output power changes monotonously with the adjustment of the operational frequency). For WPC specification, the “Qi” defines the coil inductance and resonant capacitance, the resonant frequency is fixed at 100 kHz, then power transfer can work normally by adjusting the TX operating frequency from 110 kHz to 205 kHz with fixed 50% duty cycle. Besides, the switching topology and phase shift control at breakpoint frequency would be used when charging the medium power receiver. Higher TX operating frequency means lower power transferred to RX, and lower TX operating frequency means higher power transferred to RX. The duty cycle decreases when the operating frequency reaches to 205 kHz and RX requires lower transferred power. When charging the medium power receiver, TX switches the topology to full bridge from half bridge and increases the phase shift from the initial phase shift when the operating frequency reaches the breakpoint frequency and higher transferred power is required. When the phase shift reaches 100%, the operating frequency is adjusted again. Figure 5 shows the voltage gain (voltage on resonant inductor vs. the input voltage) change with operating frequency. Voltage gain increases while operation frequency decreases. Figure 5 LC parallel resonant converter control principle 5.3 Receiver to transmitter communication In medium power wireless charging application, there is two-way communication link between the receiver and the transmitter. This section is mainly about the communication from RX to TX. WCT1012DS, Rev. 1.1, 09/2015 22 Freescale Semiconductor 5.3.1 Modulator The receiver sends the information to the transmitter by communication packages. The information includes the power requirements, received power, receiver ID and version, receiver power ratings, and charging end command. Figure 6 Load modulation scheme Figure 6 shows the modulation technologies at the RX side. RX modulates load by switching modulation resistor ( , AC side or DC side), or modulation capacitor ( , AC side). The amplitude of voltage/current on RX coil is modulated by connecting or disconnecting modulation load (resistor or capacitor). The amplitude of voltage/current on TX coil is also modulated to reflect load switching through magnetic induction. Then TX demodulates the sensed amplitude change of current ( > 15mA), or voltage ( > 200mV) on TX coil. Figure 7 shows how the RX switching modulation capacitor affects the TX resonant characteristics (Gain vs. Frequency characteristics). Figure 7 Load modulation principle The Bode diagram in Figure 7 shows that the voltage amplitude on the TX coil decreases when the modulation capacitor is connected on the RX side and the RX couples the communication signal onto the power signal through modulating power signal directly. WPC defines the modulation baud rate to 2 kbps. WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 23 5.3.2 Demodulator As the RX modulates the communication signal on the power signal, the TX has to demodulate communication signal from power signal to get the correct information sent by RX, and further control the whole system operation. Figure 8 shows the power signal (voltage) waveform coupled with communication signal on TX coil. Figure 8 TX coil voltage profile with RX modulation The WCT1012 employs software solution to implement demodulator, also called digital demodulation technology. WCT1012 directly senses the voltage on resonant capacitor through a very simple, low cost RC circuit (Figure 9), and the high-speed 12-bit cyclic ADC is capable of handling the maximum 205 kHz signal in time to assure accurate signal sampling. After the resonant capacitors voltage value is obtained, the equivalent resonant current in the coil can be calculated, and this coil current is used for the digital demodulation algorithm. After that, the WCT1012 demodulate the signal to get the packet from RX. Figure 9 Sensing circuit and waveform of TX resonant capacitor voltage With Freescale digital demodulation algorithm, the WCT1012 can support all modulation types on the RX, such as AC resistor, DC resistor, or AC capacitor. WCT1012DS, Rev. 1.1, 09/2015 24 Freescale Semiconductor 5.3.3 Message encoding scheme The WCT1012 demodulates and decodes the message sent from RX, which is encoded by differential bi-phase scheme. A logic ONE bit is encoded using two transitions in the 2 kHz clock period (500 us), and a logic ZERO bit using one transition. One Start bit, 8-bit data, one Parity bit and one Stop bit compose one message byte. A typical packet consists of four parts, namely a preamble ( 11 bits), a header (1 byte), a message (1 to 27 bytes), and a checksum (1 byte). Figure 10 shows the detailed message encoding scheme that WPC defines. Digital demodulation module in WCT1012 extracts the digital encoded communication signal from the analog power signal. a) Bit Encoding b) Byte Encoding c) Packet Structure Figure 10 WPC RX to TX communication message encoding scheme 5.4 Transmitter to receiver communication In medium power wireless charging application, there is two-way communication link between the receiver and the transmitter. TX sends messages to RX by FSK. 5.4.1 Modulator The transmitter sends information to the receiver by communication packages and patterns (ACK, NAK, ND). Packages include transmitter ID and version, guaranteed power, and potential power. The Power Transmitter modulates the power signal by switching its operating frequency between two states, namely fop and fmod. A modulation level is characterized in that frequency of the Power Signal that is constant at either fop or fmod for 256 +/- 3 cycles. The allowed change in frequency (fop or fmod) must be less than 3% over 400 ms. The equation shown in below table takes into account two variables from the Power Receivers’ configuration packet: FSKDepth and FSKPolarity. FSKDepth defines the amount that the period of the waveform must change and FSKPolarity defines whether the period must increase or decrease (0 for period decrease and 1 for increase). Table 10 Equation of fmod FSKPolarity=0 FSKPolarity=1 WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 25 The Power Transmitter modulates the Power Signal at specific time slot to avoid interrupting communication packets from the Power Receiver. The Power Transmitter may modulate the Power Signal only when responding to Request packets sent by the Power Receiver during the Negotiation phase, Calibration phase and Power Transfer phase. 5.4.2 Message encoding scheme The Power Transmitter uses a differential bi-phase encoding scheme to modulate data bits onto the Power Signal. For this purpose, the Power Transmitter aligns each data bit to 512 periods of the Power Signal frequency. The Transmitter encodes a logic ONE bit by using two transitions in the Power Signal frequency. The first transition occurs at the beginning of the bit period and the second transition occurs after 256 cycles of the Power Signal. The Transmitter encodes a logic ZERO bit by using a single transition in the Power Signal frequency and then remaining at the new frequency for 512 cycles of the Power Signal. One Start bit, 8-bit data, one Parity bit and one Stop bit compose one packet byte. A typical packet consists of three parts, namely, a header (1 byte), a message, and a checksum (1 byte). Figure 11 shows the detailed message encoding scheme that WPC defines. Besides, patterns (ACK, NAK, ND) just contain one 8-bit data, without header, checksum, Start bit and Stop bit. (a) Bit Encoding Example (b) Byte Encoding (c) Packet Format Figure 11 WPC TX to RX communication message encoding scheme WCT1012DS, Rev. 1.1, 09/2015 26 Freescale Semiconductor 5.5 System control state machine WCT1012 embeds a WPC “Qi” State Machine to process received communication message from RX and control power transfer to RX. The overall system behavior between transmitter and receiver is controlled by the state machine shown in Figure 12. Figure 12 WPC Wireless Charging System state machine 5.5.1 Selection phase During the Selection phase, the TX system runs in low power mode to judge whether an object is placed on the TX coil surface. The PING operation runs every 400 ms, and during the PING interval, the system is in the Selection phase. If the touch sensor module is enabled, WCT1012 enters deep low power mode as described in the Standby Power section. 5.5.2 Ping phase During the Ping phase, the TX system works on both analog PING and digital PING to detect a receiver placed on the TX charging area. The analog PING time is far shorter than the digital PING for power-saving purposes. The analog PING enables a very short AC pulse on the TX coil, WCT1012 reads back the coil current and compares it with the predefined current change threshold to judge whether an object is put on. The default coil current change threshold is 5%, which the user can set in FreeMASTER GUI to get good sensitivity. WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 27 For digital PING, the TX system applies a power signal at 175 kHz with 50% duty cycle to attempt to set up communication with RX. In response, RX must send out the Signal Strength packet. Signal Strength message indicates the degree of coupling between TX coil and RX coil, and is the percentage of rectifier output signal against the possible maximum PING signal. In this formula, is the monitored variable, and during digital PING. is the maximum value, which the RX expects for When the Signal Strength packet is received in the Ping phase, the system enters the Identification & Configuration phase. 5.5.3 Identification & Configuration phase In the Identification & Configuration phase, the TX system continues to identify the receiver device and collects the configuration information to establish a default power transfer contract. After receiving the configuration packet, the TX performs as follows: • If the Neg bit in the received configuration packet is set to ZERO, the TX proceeds to the power transfer phase without sending a response. • If the Neg bit in the received configuration packet is set to ONE, the TX sends an ACK response in right timing after the end of the received configuration packet. Subsequently, the TX proceeds to the negotiation phase. • If the TX does not proceed to the power transfer phase or to the negotiation phase, the TX removes the power signal in right timing after the end of the configuration packet. 5.5.4 Negotiation phase During the Negotiation phase, the Power Transmitter receives a series of Packets that contain requests to update the Power Transfer Contract. In response to each Packet, the Power Transmitter sends either of the following: • • A Response to indicate whether it grants the request, denies the request, or does not recognize the request A data packet that contains the requested information Prior to receiving the requests to update the Power Transfer Contract, the Power Transmitter creates a temporary copy of the Power Transfer Contract. The Power Transmitter uses this temporary copy to store updated parameters until successful completion of the negotiation phase. 5.5.5 Calibration phase During the calibration phase, the Power Transmitter receives information from the Power Receiver that the Power Transmitter can use to improve the power loss method for Foreign Object Detection. In WCT1012DS, Rev. 1.1, 09/2015 28 Freescale Semiconductor particular, the Power Transmitter receives the Received Power information, with the Power Receiver attached: • A “light” load • A “connected” load If the Power Transmitter does not receive this information, it removes the Power Signal and returns to the selection phase. In addition, the Power Transmitter attempts to use this information to improve its power loss method only if it ensures that there is no Foreign Object present. In the calibration phase, the behavior of the Power Transmitter is the same as in the power transfer phase, with the following additions: • If the Power Transmitter receives a 24-bit Received Power Packet with Mode = ‘001’ (calibration mode for a light load), and the Received Power Value satisfies the Power Transmitter, it sends an ACK Response. Otherwise, it sends a NAK Response. • If the Power Transmitter receives a 24-bit Received Power Packet with Mode = ‘010’ (calibration mode for a connected load), and the Received Power Value satisfies the Power Transmitter, it sends an ACK Response and proceed to the power transfer phase. Otherwise, it sends a NAK Response. • If the Power Transmitter receives a 24-bit Received Power Packet with a Mode value other than ‘001’ and ‘010’, it removes the Power Signal and returns to the selection phase. 5.5.6 Power transfer phase The MP TX can discriminate between low power RX and medium power RX. • During the Power Transfer phase, if the RX is a low power receiver, the TX configures the inverter to half bridge firstly, and then the TX system receives the Control Error packet from the RX and controls the amount of transferred power by adjusting the operating frequency in the range of 110 kHz – 205 kHz with 50% duty cycle. o If the operating frequency reaches 110 kHz and the positive Control Error value is still received (more output power required), the TX system keeps the current power output. o If the operating frequency reaches 205 kHz and the negative Control Error value is still received, the TX system decreases PWM duty cycle in the range from 50% to 10%. • During the Power Transfer phase, if the RX is a medium power receiver, the MP TX configures the inverter to half bridge firstly, and then the MP TX system receives the Control Error packet from the RX and controls the amount of transferred power by adjusting the operating frequency. When the operating frequency reaches break frequency and higher power is required, the MP TX configures the inverter to full bridge from half bridge, and then adjusts the phase shift from the initial phase shift, while the phase shift reaches 100%, the operating frequency is then adjusted again. When the operating frequency is in the 110 kHz – 205 kHz range, the duty cycle is 50%. o If the operating frequency reaches 110 kHz and the positive Control Error value is still received (more output power required), the TX system keeps the current power output. WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 29 o If the operating frequency reaches 205 kHz and the negative Control Error value is still received, the TX system decreases PWM duty cycle in the range from 50% to 10%. During the power transfer, the TX system also executes the FOD algorithm by using the Received Power packet from the RX, and the TX system always checks the timing of the Control Error packet and the Received Power packet, and whether it complies with specifications. If any violation occurs, the TX system ends the power transfer. If the mode of the Received Power packet is '000', the TX sends ACK/NAK to the RX. If the mode is '100', the responses are not needed. 5.5.7 Renegotiation phase During the renegotiation phase, the TX is the same as in the negotiation phase with the following exceptions: • If the Power Transmitter receives a Control Error Packet, Received Power Packet, or Charge Status Packet, it discards the temporary Power Transfer Contract, and returns to the power transfer phase. • If the Power Transmitter receives an FOD Status Packet, it sends an ND Response. • If the Power Transmitter has received a Specific Request Packet with Request = 0x00 (End Negotiation), it bases its Response on a verification of the Count Value only. 5.6 Standby power When there is no charging activity, the TX system enters the standby (Selection phase) mode. In standby mode, all the analog parts on the TX board are powered down by the WCT1012, and the WCT1012 itself runs in low power state during the PING interval. The WCT1012 can enter deep sleep state if Freescale GPIO Touch Sensor technology is supported in the TX system. In this use case, WCT1012 is in LPSTOP (low power STOP) state, only one GPIO touch pad, timer and CPU are periodically activated to sense the electrode capacitance change to know if an object is placed on the TX charging area. 5.7 Foreign object detection The WCT1012 solution supports the medium power FOD framework, which is based on the calibrated power loss method and quality factor (Q factor) method. WCT1012DS, Rev. 1.1, 09/2015 30 Freescale Semiconductor 6 Application Information 6.1 On-board regulator The auxiliary power supply provides the voltage source for control, sensing, communication, and MOSFET driver. In transmitter design, 3.3 V is required for the WCT1012, ADC conditioning circuits, and communication demodulation circuits. 12V input voltage is supplied for inverter pre-driver circuit. Step-Down Converter MP2314 is selected to generate 3.3 with 2A output capacity. At the same time, other type Step-Down converter can be used to meet the requirements, and the following parameters must be considered for the regulator selection. • Maximum input voltage: > 14V • Maximum output current: > 100 mA 6.2 Inverter and driver control Figure 13 Full-bridge inverter topology Figure 13 shows the schematic of full-bridge inverter. The input voltage range of this application is from 11 to 13 volts, the input current range is from 0 to 2 amps. LC resonant network is connected between the middle point (a) of bridge leg 1 and the middle point (b) of bridge leg 2. N-channel MOSFETs of Q1–Q4 are controlled by PWMs generated from WCT1012, and the operating frequency range of MOSFETs is 110 kHz to 205 kHz. In addition, the inverter can be configured as half bridge topology by normally turn on the low-side MOSFET (Q4 or Q3) and turn off the high-side MOSFET (Q2 or Q1). To meet the system efficiency and power transfer requirements, these are some suggestions for the MOSFETs and driver IC selection. • Full-bridge inverter MOSFETs: >= 30 V, < 20 mΩ for power switching application MOSFET is recommended. The MOSFET is the critical component for the system efficiency, AON7400A from AOS is selected as the main power switch, and AON7400A is a 30 V, 40 A, < 10.5 mΩ ( • = 4.5 V), N-channel power MOSFET. Driver: the synchronous BUCK driver IC or bridge driver IC can meet the requirements for the full-bridge inverter. The driver IC handles 14 V voltage input for some de-rating applications. The WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 31 synchronous BUCK driver IC is recommended for this application because of good cost advantage, so NCP3420DR2G is selected on this design. This driver IC has the following features: o Maximum main supply voltage input is 15V. o Very short propagation delay from input to output (less than 30 ns). o 2 channels PWM can be controlled by WCT1012 independently. o Safety Timer and Overlap protection circuit. 6.3 Primary coil and resonant capacitor The resonant network is shown in Figure 14, which is the basic LC series resonant network circuit. The section of “Power Transfer” in chapter of “Wireless Charging System Operation Principle” describes the basic operation process of LC resonant inverter. For the design principles of resonant components parameters, consider two points: • Set a fixed resonant frequency (WPC defines it as 100 kHz) • Configure a suitable Q (quality factor) value to output required power in specific operational range like WPC-15W1COILTX type, = 276 nF, = 8.9uH, this resonant network parameters can meet the medium power (15 W) wireless charger requirements under defined operational conditions. Figure 14 Schematic resonant network circuit and are connected in series, the resonant frequency of WPC-15W1COILTX resonant network can be obtained: The electrical and mechanical features of the TX coil are defined in details. Figure 15 shows the mechanical features of WCT-15W1COILTX coil type. WCT1012DS, Rev. 1.1, 09/2015 32 Freescale Semiconductor Parameter Symbol Value Shield Inductance Lp 8.9uH±10% Outer diameter do 48.5±1.0mm Inner diameter di 23.0±1.0mm Thickness dc 2.0±0.5mm Number of turns per layer N 11 Number of layers - 1 Shielding materials - Soft-magnetic materials Figure 15 WCT-15W1COILTX round coil mechanical features For resonant capacitor, COG ceramic capacitor is selected to meet the critical system requirements, because the capacitance affects the resonant frequency of resonant network, 5% tolerance is allowed for the whole system operation. This capacitance with WCT-15W1COILTX coil can achieve the 100 kHz resonant frequency. Three types of capacitors are recommended to select: • Murata: GRM3195C2A333JA01D – 1206 –100V – 33nF (2 pcs) • Murata: GRM31C5C2A104JA01L –1206-100V – 100 nF (2 pcs) • Murata: GRM3195C2A103JA01 – 1206 –100V – 10nF (1 pcs) WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 33 6.4 Low power control To achieve low power consumption, the driver and analog circuits power are shut down when the system is in standby mode or interval time between the PINGs. AUXP_CTRL signal is designed to achieve this target. Figure 16 shows the typical application circuit to control VDRIVER and AVCC_Q on or off. Figure 16 Low power control circuit The power source of the inverter drivers and current sensor amplifier and Q factor detection circuits can be controlled by the above circuit. This circuit is still benefited from the Touch Sensor technology. When the TX goes to the standby mode, the WCT1012 enters deep sleep mode, and the power of the driver and analog circuits is shut down by the AUXP_CTRL signal. 6.5 GPIO touch sensor Figure 17 Basic theory of capacitive touch sensor Capacitive touch sensor is selected in this design, and an additional electrode touch pad is designed to sense the placement of mobile device. When the mobile device is put on the TX coil, GPIO touch sensing detects the capacitance change on the pad, and then enters digital PING phase for device identification. Figure 17 shows the basic theory for this method. Because of FOD function, this electrode touch pad should not be placed on the top of the TX coil, and 5 mm XY (horizontal) distance is required between the TX coil and the electrode touch pad. 6.6 ADC input channels To sense the necessary analog signals in the TX system, 5 ADC input channels are designed for these analog signals, and 1 DAC output channel is used for Q factor detection. This list describes the design details of these analog signals in the default setting. For the specific circuits, see the system example design schematics. WCT1012DS, Rev. 1.1, 09/2015 34 Freescale Semiconductor • Input voltage: 154 kΩ and 20 kΩ resistors to divide the input voltage, and when the Q factor detection is enabled, the 20 kΩ resistor is disconnected. • Temperature: 100 kΩ NTC (NCP15WL104E03RC) and 51 kΩ resistors are recommended to sense the temperature of board or coil (over-temperature protection point: 60°C @ 0.94 ADC input). • Input current: 15 mΩ current sensing resistor and 1:100 current sensor (CS30CL) are recommended. • Q_TEST: Operational amplifier and analog switch are used for Q factor detection. • Coil current: The resistors are used to divide the resonant capacitor voltage. The scale is changed when GAIN_SWITCH is enabled. 6.7 Faults handling/recovery WCT1012 supports several types of fault protections during the TX system operation, including the FOD fault, TX system fault, and RX device fault. According to the fault severity, the faults are divided into several rates: fatal fault, immediate retry fault, and retry fault after several minutes. The fault thresholds and time limits are described in the WCT1012 15W V3.0 Single Coil TX Runtime Debugging User’s Guide (WCT1012V30RTDUG). Table 11 lists all the available fault types and their corresponding fault handlings. Table 11 System faults handling Types Name Handling Recovery wait time Conditions Description FOD Fault FOD fault TX system shuts off after fault lasts 1 second Wait 5 minutes or RX removed 1, Power loss base threshold 2, Power loss indication to power cessation 3, Power loss fault retry times Foreign object is detected and lasts for the defined time. The system shuts off, and waits for recovery time or RX removed to enable power transfer. The time limit can be configured by user. TX System Fault Hardware fault (ADC, Chip) TX system shuts off immediately No retry any more - Once hardware fault happens, the TX system shuts off forever. EEPROM corruption fault TX system shuts off immediately No retry any more - The WCT1012 checks data validity of EEPROM after power on, stop running forever if EEPROM is corrupted. Input over-voltage TX system shuts off immediately No retry any more Safety input threshold When input voltage exceeds the threshold, the TX system shuts off immediately and waits for recovery time to enable power transfer. WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 35 RX Device Fault 6.8 Input over-power TX system shuts off immediately Wait for 5 minutes or RX removed Input power threshold When input power exceeds the threshold, the TX system shuts off immediately and waits for recovery time to enable power transfer. Coil over-current TX system shuts off immediately Retry immediately Coil current threshold When coil current exceeds the threshold, the TX system shuts off immediately and tries PING again. TX over-temperature TX system shuts off immediately Wait for 5 minutes or RX removed Temperature threshold When the temperature on the board or the coil exceeds the threshold during power transfer, the TX system shuts off immediately and waits for recovery time or RX removed to enable power transfer. RX internal fault (EPT-02) TX system shuts off immediately No retry any more - The TX system shuts off forever if End Power packet is received and End Power code is internal fault. RX over-temperature (EPT-03) TX system shuts off immediately Wait for 5 minutes or RX removed - The TX system shuts off and waits for recovery time to enable power transfer if End Power packet is received and End Power code is over temperature. RXover-voltage (EPT-04) TX system shuts off immediately Retry immediately or RX removed - The TX system shuts off and tries PING again if End Power packet is received and End Power code is over voltage. RX over-current (EPT-05) TX system shuts off immediately Retry immediately - The TX system shuts off and tries PING again if End Power packet is received and End Power code is over current. RX battery failure (EPT-06) TX system shuts off immediately No retry any more - The TX system shuts off forever if End Power packet is received and End Power code is battery failure. LEDs function Two pins (user can re-configure them to different configuration ports) on WCT1012 are used to drive LEDs for different system status indication in this design, such as charging, standby and fault status, etc. The LEDs can work on different functions using software configuration. WCT1012 controls the LEDs on/off and blink according to the parameters configuration under different system status. For how to WCT1012DS, Rev. 1.1, 09/2015 36 Freescale Semiconductor configure LED functions by the FreeMASTER GUI tool, see the WCT1012 15W Single Coil TX Reference Design System User’s Guide in the WCT-15W1COILTX reference design platform. The suggested LED functions are listed in the below table for different system status indication. Table 12 System LED modes LED configuration option Description Default Default choice LED 1 Off LED 2 Choice 1 Option 1 Option 2 Option 3 6.9 LED # LED operation state Standby Choice 2 Choice 3 Charging Charge complete FOD fault TX fault RX fault Blink slow Off On On On Blink slow On On Off Off Off LED 1 Off Blink slow On Off Off Off LED 2 Off Off Off Blink fast Blink fast Blink fast LED 1 Off On Off Off Off Off LED 2 Off Off Off On Blink slow Blink slow LED 1 Off Blink slow On Blink fast Blink fast Blink fast LED 2 - - - - - - Configurable pins The WCT1012 supports pin multiplexer, which means that one pin can be configured to different functions. If the default on-chip functions are not used in your applications, such as GPIO touch sensor, and ultra low power control, these pins can be configured for other functions. Table 13 lists the pin multiplexer for WCT1012 configurable pins. Table 13 Configurable pins multiplexer Pin No. Default Function Alternative Function 3 TEMP_S GPIO 4 TOUCH_S GPIO 5 LED1 GPIO 15 GAIN_SWITCH GPIO 16 RXD0 GPIO 17 TXD0 GPIO 18 GPIO - 19 LED2 GPIO 23 GPIO - 25 AUXP_CTRL GPIO 26 DRIVER_EN GPIO WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 37 6.10 Unused pins All unused pins can be left open unless otherwise indicated. For better system EMC performance, it is recommended that all unused pins are tied to system digital ground and flooded with copper to improve ground shielding. 6.11 Power-on reset WCT1012 can handle the whole system power on sequence with integrated POR mechanism, so no more action and hardware is needed for the whole system powered on. 6.12 External reset WCT1012 can be reset when the pin is pull down to logic low (digital ground). A 4.7 kΩ pull-up resistor to 3.3 V digital power and a 0.1 uF filter capacitor to digital ground are recommended for the reliable operation. This pin is used for the JTAG debug and programming purpose in this design. 6.13 Programming & Debug interface One JTAG and one QSCI communication ports are designed for the communication with the PC. JTAG is used for the system debug, calibration, and programming. And QSCI is used for the communication with the PC to display the system information, such as input voltage, input current, coil current, and operating frequency. For the hardware design, see the system example design schematics. 6.14 Software module The software in WCT1012 is matured and tested for production ready. Freescale provides a Wireless Charging Transmitter (WCT) software library for speeding user designs. In this library, low level drivers of HAL (Hardware Abstract Layer), callback functions for library access are open to user. For the software API and library details, see the WCT1012 15W Single Coil TX Reference Design System User’s Guide in the WCT-15W1COILTX reference design platform. 6.14.1 Memory map WCT1012 has 48 Kbytes on-chip Flash memory and 8 Kbytes program/data RAM. Besides for wireless transmitter library code, the user can develop private functions and link it to library through predefined APIs. Table 14 WCT1012 memory footprint Memory Total size Example code size Library size FreeMASTER size Free size Flash 48 Kbytes 40.8 Kbytes 26.8 Kbytes 1.5 Kbytes 7.2 Kbytes RAM 8 Kbytes 4.67 Kbytes 3.4 Kbytes 0.1 Kbytes 3.33 Kbytes WCT1012DS, Rev. 1.1, 09/2015 38 Freescale Semiconductor 6.14.2 Software library The WCT software library provides the complete wireless charging function which is compliant with the latest version WPC “Qi” specifications. This library includes the “Qi” communication protocol, power transfer control program, FOD algorithm using power loss method, system status indication module, and fault protection module. Figure 18 shows the complete software structure of this library. A data structure in the software library can be accessed by user code, which contains runtime data like input current, input voltage, coil current, PWM frequency and duty cycle. For the details of how to use this library, the API definitions, and the data structure, see the WCT1012 TX Library User’s Guide in the WCT-15W1COILTX reference design platform. In addition, a FreeMASTER calibration module is integrated into this library, which enables the end product customization and FOD calibration through the QSCI port. Figure 18 Software structure of WCT library 6.14.3 API description Through WCT library APIs, the user can easily get the typical signals on TX system, such as the input voltage, input current, coil current, and PWM frequency etc. The user can conveniently know WCT1012 operational status by watching variables through the FreeMASTER GUI tool. For more information about API definitions, see the WCT1012 TX Library User’s Guide in the WCT-15W1COILTX reference design platform. WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 39 6.15 Example design schematics Go to Freescale website freescale.com and search “WCT1012” to find the schematic details and the WCT-15W1COILTX user guide. WCT1012DS, Rev. 1.1, 09/2015 40 Freescale Semiconductor 7 Design Considerations 7.1 Electrical design considerations Use the following list of considerations to assure correct operation of the device and system: • The minimum bypass requirement is to place 0.01 - 0.1 μF capacitors positioned as near as possible to the package supply pins. The recommended bypass configuration is to place one bypass capacitor on each of the VDD/VSS pairs, including VDDA/VSSA. Ceramic and tantalum capacitors tend to provide better tolerances. • Bypass the VDD and VSS with approximately 10 μF, plus the number of 0.1 μF ceramic capacitors. • Consider all device loads as well as parasitic capacitance due to PCB traces when calculating capacitance. This is especially critical in systems with higher capacitive loads that could create higher transient currents in the VDD and VSS circuits. • Take special care to minimize noise levels on the VDDA, and VSSA pins. • Using separate power planes for VDD and VDDA and separate ground planes for VSS and VSSA are recommended. Connect the separate analog and digital power and ground planes as near as possible to power supply outputs. If an analog circuit and digital circuit are powered by the same power supply, you should connect a small inductor or ferrite bead in serial with VDDA traces. • If desired, connect an external RC circuit to the RESET pin. The resistor value should be in the range of 4.7 kΩ – 10 kΩ; and the capacitor value should be in the range of 0.1 μF – 4.7 μF. • Add a 2.2 kΩ external pull-up on the TMS pin of the JTAG port to keep device in a restate during normal operation if JTAG converter is not present. • During reset and after reset but before I/O initialization, all I/O pins are at input mode with internal weak pull-up. • To eliminate PCB trace impedance effect, each ADC input should have a no less than 33 pF/10 Ω RC filter. • Need some optional circuits for the power saving function, those circuit can be removed when the design is not sensitive for this requirements, so the GPIO touch sensor and AUXP_CTRL can be removed. 7.2 PCB layout considerations • Provide a low-impedance path from the board power supply to each VDD pin on the device and from the board ground to each VSS pin. • Ensure that capacitor leads and associated printed circuit traces that connect to the chip VDD and VSS pins are as short as possible. WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 41 • PCB trace lengths should be minimal for high-frequency signals. • Physically separate analog components from noisy digital components by ground planes. Do not place an analog trace in parallel with digital traces. Place an analog ground trace around an analog signal trace to isolate it from digital traces. • The decoupling capacitors of 0.1 μF must be placed on the VDD pins as close as possible, and place those ceramic capacitors on the same PCB layer with WCT1012 device. VIA is not recommend between the VDD pins and decoupling capacitors. • The WCT1012 bottom EP pad should be soldered to the ground plane, which makes the system more stable, and VIA matrix method can be used to connect this pad to the ground plane. • As the wireless charging system functions as a switching-mode power supply, the power components layout is very important for the whole system power transfer efficiency and EMI performance. The power routing loop should be as small and short as possible, especially for the resonant network. The traces of this circuit should be short and wide, and the current loop should be optimized smaller for the MOSFETs, resonant capacitor and primary coil. Another important thing is that the control circuit and power circuit should be separated. 7.3 Thermal design considerations WCT1012 power consumption is not so critical, so there is not additional part needed for power dissipation. But the full-bridge inverter needs the additional PCB Cu copper to dissipate the heat, so good thermal package MOSFET is recommended to select, such as DFN package, and for the resonant capacitor, COG material, and 1206 package is recommended to meet the thermal requirement. The transmitter system internal power loss is about 1.5 W with full 15 W loads, and the hottest part is on the inverter, so the user should make some special action to dissipate the heat. Figure 19 shows one thermal strategy for the inverter. WCT1012DS, Rev. 1.1, 09/2015 42 Freescale Semiconductor Cu copper for heat dissipation of the inverter MOSFET Cu copper for heat dissipation of input capacitors Cu copper for heat dissipation of resonant capacitors Figure 19 Thermal design strategy for inverter WCT1012DS, Rev. 1.1, 09/2015 Freescale Semiconductor 43 8 Links • freescale.com • freescale.com\wirelesscharging • www.wirelesspowerconsortium.com WCT1012DS, Rev. 1.1, 09/2015 44 Freescale Semiconductor How to Reach Us: Home Page: freescale.com Web Support: freescale.com/support Information in this document is provided solely to enable system and software implementers to use Freescale products. There are no express or implied copyright licenses granted hereunder to design or fabricate any integrated circuits based on the information in this document. Freescale reserves the right to make changes without further notice to any products herein. Freescale makes no warranty, representation, or guarantee regarding the suitability of its products for any particular purpose, nor does Freescale assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters that may be provided in Freescale data sheets and/or specifications can and do vary in different applications, and actual performance may vary over time. All operating parameters, including “typicals,” must be validated for each customer application by customer’s technical experts. Freescale does not convey any license under its patent rights nor the rights of others. Freescale sells products pursuant to standard terms and conditions of sale, which can be found at the following address: freescale.com/SalesTermsandConditions. Freescale and the Freescale logo are trademarks of Freescale Semiconductor, Inc., Reg. U.S. Pat. & Tm. Off. All other product or service names are the property of their respective owners. ©2015 Freescale Semiconductor, Inc. Document Number: WCT1012DS Rev. 1.1 09/2015